Tubular ball-mill.



Patented'Nov. [2, I905; P. T. LINDHARD.

TUBULAR BALL MILL. I

(Application filed Dec. 28, 1900.)

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ATTORNEYS.

P. T. LINDHABD.

TUBULAR BALL MILL.

(Application filed Dec. 98, 1900.)

(No Model.)

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ATTYS screened center outlet, at approximately the UNITED STATES POVL T.LIN DHARD, OF RICHMOND HILL, NEW YORK, ASSIGNOR TO F. L.

PATENT OFFI E.

SMIDTH & COMPANY, OF NEW YORK, N. Y., CORPORATION.

TUBULAR BALL-MILL.

SPECIFICATION forming-part of Letters Patent No. 686,621, dated November12, 1901.

Application filed December 28, 1900. Serial No. 41,331. (No model.)

To a. whom it may concern.-

Be it known that I, PovL' T. LINDHARD, a citizen of the Kingdom ofDenmark, residing in Richmond Hill, in thevcity of New York, borough ofQueens, inthe State of New York, have invented certain new and usefulImprovements in Tubular Ball-Mills, of which the following is aspecification.

This invention relates to improvements in tubular ball-mills, and moreespecially to mills designed for grinding material in a semiliquid orpasty condition-such, for instance, as that known in the cement industryas slurry. In a dry mill, or one designed for grinding material in a drystate, good results are obtained when the dischargeopenings are arrangednear the circumference of the discharge-head; but this construction isnot adapted for a wet mill, because when the mill is stopped a quantityof the unground or. partly-ground material, termed grit, will drainoutwith the prop erly-ground product. Neither is a plain same level asthe inlet, suitable, though overcoming this disadvantage, because theecon-' omy of the mill depends upon the gradual and progressivedistribution of the material among the balls, and this is not easilyobtainable with such an outlet. There was with such an outlet danger ofover-filling the mill, while circumferential openings possessed thecontary disadvantage that it was not possible to work the mill to itsfull capacity owing to the greater fluidity of wet as compared to drymaterial.

The object of this invention is to provide means for overcoming theseobjections; and for this purpose the invention consists in thecombination in a tubular ball-mill,with a grinding-drum having an inlet,of a screenplate in said drum having perforations below the level of theinlet, grinding-balls in the drum, and a dischargecone embracing saidperforations within its base, said cone rising-between the base and apexabove the level of the lowermost perforations.

The invention consists, further, in certain other combinations of partsmore fully described hereinafter and claimed.

In the accompanying drawings, Figure 1 is a side elevation of myimproved mill. Fig. 2 is a section on line 2 2, Fig. 1, with theperforated portion of the screen-plate removed. Fig. 3 is averticalsection on line 3 3, Fig. 2, with the perforated portion of thescreen-plate in place; and Fig. 4 is a vertical central section throughthe mill, showing the relative heights of the inlet and outlet and theopenings in'the screen-plate.

Similar letters of'refere'nce indicate corresponding parts.

Referring to the drawings, A indicates the drum orjtube of a tubularball-mill of any approved construction and provided at the interior withgrinding-balls in the usual manner. The drum is provided with aninlet-head B,havinga tubular shaft or gudgeon b,serving as theinlet,which communicates with a feed-pipe B, through which the materialto be ground is fed. The outgoing head G of the mill is at tached to thedrum by bolts (1' or otherwise and is provided with a tubular shaft orgudgeon c,preferably tapering outwardly at its interior and serving asthe outlet of the drum to which is connected the discharge-pipe ct.

At the outgoing end of the drum is arranged a screen- .plate DE,preferably made with its perforated portion E detachable from theclosed portion D; but it may be made in one or any desired number ofpieces and secured either to the drum or to the outgoing head 0, asshown by bolts c,or in any other suitable manner. The lowermostperforations-4. a, those at the greatest radiusfrom the axis of themillare located below the level of the inlet, and the level of theoutlet is above the level of said perforations, as shown in Fig. 4.

Between the screen-plate and the outlet of the mill, in line with theoutlet, is located a discharge-cone F, which communicates at its apexwith the outlet and at its base with said perforations. In said cone arearranged conveyer-blades G, which serve as'means for conveying theground material through the cone. The cone may be attached to thescreen-plate by bolts f engaging the flange f of the cone and to thehead 0 by bolts f engaging flange f of the cone or in any other suitablemanner. When the cone is attached to the mill so as to rotatetherewith,the motive power of the latter serves through the mill asmeans for rotating theconeandconveyer-blades. The conveyorblades may bepositively secured in the cone in any suitable manner; but they willordinarily have some spring tension and in this case will retain theirposition therein by friction with the same, so as to rotate with thecone without slip.

The necessary gradual distribution of the material among the balls issecured by my improved construction by reason of the fact that thematerial is discharged through the screenplate at a lower level thanthat at which it enters the drum. \Vhen the mill is stopped, no materialwill flow out of the same; butin leveling itself in the mill a smallportion of the material nearest the cone will enter the cone and whenthe mill is again started will be conveyed out of the same; but as thisportion has been almost completely ground and owing to the fact that thecone tapers from the perforations to the outlet is small in quantity itdoes not materially affect the uniform character of the product. Theconveyer-blades are made of greater width at their outer ends adjacentto the screen-plate than at their inner ends, as shown in'Fig. 4, and ofsufficient height so that they serve to block the entrance of thematerial into the cone when leveling itself in the mill after stoppingthe same. The thicker the material to be ground the nearer to thecircumference of the screen-plate can the perforations of the same bemade, and by inserting different cones and regulating the size andnumber of holes in the screen-plate the mill can be made to grind amaterial containing any given amount of moisture with the highesteconomy.

Having thus described my invention, I laim as new and desire to secureby Letters Patent- 1. In a tubular ballmill, the combination, with agrinding-drum having an inlet, of a screen-plate in said drum havingperforations below the level of the inlet, grinding-balls in the drum,and a discharge-cone communicating with the outlet and embracing saidperforations within its base, said cone rising between its base and apexabove the level of the lowermost of said perforations, substantially asset forth.

2. In a tubular ball-mill, the combination, with a grinding-drum havingan inlet, of a screen-plate in said drum having perforations below thelevel of the inlet, grinding-balls in the drum, and a discharge-conecommunicating with the outlet and embracing said perforations within itsbase, said cone rising between its base and apex above the level of thelowermost of said perforations, and means forconveying material throughsaid cone, substantially as set forth.

3. In a tubular ball-mill, the combination, with a grinding-drum havingan inlet, of a screen-plate in said drum having perforations below thelevel of the inlet, grinding-balls in the drum, a discharge-conecommunicating with the outlet and embracing said perforations within itsbase, said cone rising between its base and apex above the level of thelowermost of said perforations, and conveyorblades in said cone,substantially as set forth.

4. In a tubular ball-mill, the combination, with a grinding-drum havingan inlet, of a screen-platein said drum having perforations below thelevel of the inlet, grinding-balls in the drum, a discharge-conecommunicating with the outlet and embracing said perforations within itsbase, said cone rising between its base and apex above the lowermost ofsaid perforations, conveyer-blades in said cone, said blades being attheir inner ends adjacent to the screen-plate of suflicient width toblock the entrance of material into the cone when the mill is stopped,substantially as set forth.

5. In a tubular ball-mill, the combination, with a grinding-drum havingan inlet, of a screen-plate in said drum having perforations below thelevel of the inlet, grinding-balls in the drum, a discharge-conecommunicating with the outlet and embracing said perforations within itsbase, and conveyor-blades in said cone, and abutting at their inner endsagainst said screen-plate, substantially as set forth.

6. In a tubular ball-mill, the combination, with a grinding-drum havingan inlet, of a screen-plate in said drum having perforations below thelevel of the inlet, grinding-balls in the drum, a discharge-conecommunicating with the outlet and embracing said perforations within itsbase, and conveyer-blades in said cone, said conveyer-blades havingspring tension and frictionally engaging the sides of the cone,substantially as set forth.

In testimony that I claim the foregoing as my invention 1 have signed myname in presence of two subscribing witnesses.

POVL T. LINDHARD.

Witnesses:

PAUL GOEPEL, GEORGE E. GEIBEL.

